The first thing that strikes you about the music of Jeremy Dale Roberts is its concentration and economy. It is music of absolute integrity, always sensitive to the tiniest musical gesture, and never showy or pandering to fashion.

It has the uncanny ability to make a very few notes tell - as if the fewer notes there are, the more is being said. His work has been described as "interior in nature and very reflective", and though often jewel-like, intimate and private, it is also uncompromising: the listener cannot get too comfortable, for there could be an outburst around the corner.

Some of his most characteristic pieces come in the form of a series of miniatures in which bold or fleeting utterances (and equally importantly, the silences that punctuate them) become microcosms, grains of sand in which a world might be glimpsed. His music is informed by a profound fascination with visual art; a case in point is the piano work Oggetti - Omaggio a Morandi (2003), in which the restrained, hermetic world of the Italian artist finds a ready musical response.

The dignity and mute eloquence of Morandi's objects - bottles, jugs and pitchers disposed as if in a family photograph - is reflected in understated yet powerful music that somehow forces you into a slower pace of listening.

Karen Wilkin's remarks, in her monograph on Morandi, could apply equally well to Dale Roberts: "For anyone who pays attention, the microcosm of Morandi's tablecloth becomes vast, the space between objects immense, pregnant, and expressive ... The austere gives way to the seductive."

Just as it would be reductive to pigeonhole Morandi as an artist who only painted jugs, so Dale Roberts' compositional concerns are by no means restricted to miniaturism.

In Tombeau (1966-69), the sequence of studies and variations lasting some half an hour that he composed for the pianist Stephen Bishop-Kovacevic, we find him having a conversation with traditions of pianistic virtuosity, specifically of the sort found in Schumann and Szymanovsky.

In Croquis (1976-80), another large-scale work, the virtuosity is of a different kind: volatile, sinuous and intense, in response to the performing temperament of the members of the Arditti String Quartet for whom it was written.

When recently I asked Dale Roberts whether his views on virtuosity had changed since composing these pieces, his reply (characteristically) invoked the other arts; this time with a quotation from Constantin Brancusi, recounted to him by the sculptor's former mistress, Vera Moore: "The arts have never existed by themselves (outside of folklore); they have always been a prerogative of the religious, and every time religion has been in decline, art has fallen into virtuosity. To make art which is truly independent, one must be God to create it, a king to order it, and a slave to realise it".

Drama and theatricality are also recurring themes in his work: in the highly charged Cello Concerto Deathwatch, which Dale Roberts wrote in 1971-74 for Rohan de Saram, the soloist is complemented by a "Doppelgänger" - another cellist, hidden from view, whose amplified sound reflects, mocks or tyrannises the soloist.

Central to the structure of this work is Rilke's idea of Wendung, or the deep, sudden change that may occur at a moment of darkest confusion. The idea of mirroring, which is further manifest in the symmetrical layout of the orchestra, was suggested by Cocteau's film Orphée, a factor that may also have influenced his conception of the piece as a "composition in black and white".

Theatrical elements are again present in works such as Stelæ (2003), commissioned by the Royal College of Music Gamelan, in which a kind of ritual is enacted by an ensemble of some 20 Javanese gongs with two drummers, again antiphonally arrayed. None of these pieces, however, betray much about the composer's origins.

Jeremy Dale Roberts was born in Gloucestershire in 1934, the same year that Elgar, Delius and Holst died. The prevailing musical culture of the time was that of the English Pastoral school and the Three Choirs Festival, whose ethos was, as he puts it, genetically imprinted on him. When he began to show interest in composition his godmother, who ran a small local music festival (and had been a friend of Holst) was able to introduce him to some of the leading composers of the time: he came to know both Finzi and Vaughan Williams well, receiving from them encouragement and advice on his music.

As a student at the Royal Academy of Music he studied with William Alwyn and Priaulx Rainier. Rainier was a South-African born composer and in many ways an outsider, progressive and radically at odds with the accepted norms of English music. It was she who challenged and stretched him, broadening his horizons with her more international outlook, Stravinskian aesthetic and rigorous technical approach. From her he inherited a muscularity and rhythmic vitality in his composition, as well as the economy that persists to this day.

After two years out, spent in the highlands of Cameroon, Dale Roberts returned to London to teach composition at Morley College - the same class that was taught over the years by composers such as Sir Michael Tippett and Sir Harrison Birtwistle. It was unusual in being open to all, and the students there included housewives, doctors, mathematicians, psychiatrists, and retired people: it was, says Dale Roberts, probably the most rewarding teaching he was ever engaged in.

Occasional extra work as a pianist and teacher brought encounters with figures such as harmonica legend Larry Adler, to whom he taught orchestration, and Bernard Herrmann, for whom he worked as a "répétiteur", note-bashing for the lead singer in the midst of some fraught recording sessions for Herrmann's opera Wuthering Heights in Barking Town Hall.

The 1960s were a time of great cultural awakening in Britain. The work of artists such as Fellini, Beckett, Cage and Merce Cunningham was coming to be known, and the avant-garde and experimental were well supported - and not necessarily tamed - by the state.

At the BBC, Sir William Glock was programming music by the more progressive European composers, and the works of Messiaen, Boulez, Stockhausen and Berio were introduced to British audiences for the first time. It was an extraordinarily stimulating environment, and Dale Roberts responded with works such as Reconciliation for Speaker and Musicians (1969), which uses specially written texts to explore a kind of no-man's-land between semantics, phonetics and instrumental "speech".

In 1966, he joined the composition staff at the Royal College of Music, where he was to remain, latterly as Head of Composition, for over 30 years. As the composer Erika Fox, who studied with him in the 60s, points out: "It's extremely difficult to teach composition. While compositional techniques, the study of other composers' works, historical perspectives etc, are a necessary part of the process, the real difficulties lie in discerning what another person actually wants to say, however obscurely expressed, so that one can point that person towards forging a language in which to say those things."

Dale Roberts has a rare gift for precisely this, alongside an uncanny ability to divine what will be useful for the student at a particular stage in their development and point them in the right direction. As well as concrete musical guidance this often yields a surprising list of new artistic avenues to be explored, whether it's the novels of Virginia Woolf or Proust, the poetry of Saint John Perse or Tsvetayeva, or the music of Prefab Sprout or KD Lang. As Erika Fox comments: "It is often said that good composers make bad composition teachers, because the temptation to impress one's own ways of thinking is too strong: Dale Roberts demonstrates that such an assumption is false. His own music is utterly individual, deeply moving and deeply felt."

Now celebrating his 70th birthday, and with several new and exciting works in the pipeline, his music is at last beginning to receive the attention it deserves.

· Lontano celebrates Jeremy Dale Roberts's 70th birthday with a concert of his works at the Purcell Room, London (020-7960 4242), on May 30. The composer is featuring in Tate St Ives Music Week, Cornwall (01736 791114), September 7-14.